LP3907SQ-JXQXEV National Semiconductor, LP3907SQ-JXQXEV Datasheet - Page 9

• Manufacturer Part Number: LP3907SQ-JXQXEV
• Description: LP3907 EVALUATION BOARD
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LP3907SQ-JXQXEV

• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 4, Non-Isolated
• Current - Output: 1A, 600mA, 300mA, 300mA
• Regulator Topology: Buck
• Frequency - Switching: 2.1MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LP3907
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Output: -
• Voltage - Input: -
• Power - Output: -

Using the Evaluation Hardware
POWERING THE LP3907 BOARD
We recommend that the user power the LP3907 through an
external power supply if any loads are attached to the regu-
lators. In case no external power supply is available (as for
showroom purposes), the USB interface can be used to pow-
er the chip.
External supply
The LP3907 Evaluation board can be powered using a battery
or wall adapter as described in previous sections. Simply ap-
ply the voltage to the VDD_M pin referenced to GND_M.
Before applying power to VDD_M, be sure to disconnect
the USBPOWER jumper. Failure to do so may damage the
USB chip and/or the IC. Full functionality of the GUI will still
be available if powered by an external power supply.
Also note that if the supply to VDD_M is close to 2.8V with a
heavy load current on the regulators, the chip is in danger of
FIGURE 10. USB Interface Settings
9
powering down due to UVLO. To disable UVLO, check the
“Bypass UVLO” feature.
USB Interface Supply
In case the external supply or battery is not available, the USB
board can be used to power the LP3907 chip. Simply connect
the USBPOWER jumper to the 5V pin on the LP3907 evalu-
ation board.
NOTE: External power supplies should be DISCONNECT-
ED from the VDD_M pin if powering from the USB.
The USB interface card can provide the following voltages :
•
•
5V from USB interface (default setting) -- USBPOWER
needs to be set to 5V
3.3V -- USBPOWER needs to be set to 3.3V. Useful if the
user wants to provide a lower voltage to the IC.
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